IDS Security engineers Manoj Mohan & Lynette D. Adayilamuriyil have written a new developerWorks article Column-level encryption in IDS - Protect your sensitive data by using the column-level encryption (CLE) feature of IBM Informix® Dynamic Server (IDS) 10 and later. It's an accessible introductory article which includes using Column Level Encryption from Dbaccess, via a simple ESQL/C program, examples of using password hints, and how to calculate storage requirements for encrypted data.
Keeping to the topic of security Fernando Nunes recently wrote a detailed article on how to setup an IDS instance to use an Active Directory or OpenLdap server as its authentication infra-structure on his Informix-Technology blog. It includes screen-shots of setting up a Windows Server 2003 as an Active Directory Server. Well worth checking out: Informix user authentication: PAM for the rescue (part 1)